Adds a linter command for templates

CHANGELOG-2.1.md

@@ -148,6 +148,7 @@ To get the diff between two versions, go to https://github.com/symfony/symfony/c
 ### TwigBundle
 
  * added the real template name when an error occurs in a Twig template
+ * added the twig:lint command that will validate a Twig template syntax.
 
 ### WebProfilerBundle
 

src/Symfony/Bundle/TwigBundle/Command/LintCommand.php

@@ -0,0 +1,87 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\TwigBundle\Command;
+
+use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * Command that will validate your template syntax and output encountered errors.
+ *
+ * @author Marc Weistroff <marc.weistroff@sensiolabs.com>
+ */
+class LintCommand extends ContainerAwareCommand
+{
+    protected function configure()
+    {
+        $this
+            ->setName('twig:lint')
+            ->setDescription('Lints a template and outputs eventual errors.')
+            ->addArgument('filename')
+            ->setHelp(<<<EOF
+the <info>%command.name%</info> command lints a template and outputs to stdout
+the first encountered syntax error.
+
+<info>php %command.full_name% filename</info>
+
+The command will get the contents of "filename" and will validates its syntax.
+
+<info>cat filename | php %command.full_name%</info>
+
+The command will get the template contents from stdin and will validates its syntax.
+
+This command will return these error codes:
+  - 1 if template is invalid
+  - 2 if file doesn't exists or stdin is empty.
+EOF
+        )
+        ;
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $twig = $this->getContainer()->get('twig');
+        $template = null;
+        $filename = $input->getArgument('filename');
+
+        if ($filename && !is_readable($filename)) {
+            $output->writeln(sprintf('<error>File %s is not readable</error>', $filename));
+
+            return 2;
+        }
+
+        if ($filename) {
+            $template = file_get_contents($filename);
+        } else {
+            if (0 !== ftell(STDIN)) {
+                $output->writeln(sprintf('<error>Please provide a filename or pipe template content to stdin.</error>'));
+
+                return 2;
+            }
+            while (!feof(STDIN)) {
+                $template .= fread(STDIN, 1024);
+            }
+        }
+
+        try {
+            $twig->parse($twig->tokenize($template));
+        } catch(\Twig_Error_Syntax $e) {
+            $output->writeln($e->getMessage());
+
+            return 1;
+        }
+
+        $output->writeln("<info>Template's syntax is valid.</info>");
+    }
+}
+